How to decide on counting direction in a clock?

[anoop12]

hello all
I am anding two clocks a and b. a is upcounting clock and b is a down counting clock.
The resulting clock c is the clock that I have to use in my code.My problem is how to
decide whether the resulting clock is for up counting or down counting. what circuit
should I implement so that I will get direction of counting?


----------
a ----> | 2 input |------> c
b ----> | and gate |
------------

a ----> ----------
| flag ckt ?? | -----> direction bit
b ----> ----------

regards

 

[avimit]

Re: counting direction

1.) Why are you anding clocks, who has advised you to do that. I believe that isn't a good idea, if you are doing it to do an up/down counter.
2. There will be a single clock going to the up/down counter, and the direction of the count should be controlled by another signal/port say direction_up_down.
There is no answer to your question.
kr,
Avi
http://www.vlsiip.com

 

[anoop12]

Re: counting direction

hi avimit,
I am designing 74193 synchronous up down counter. There they have used two clocks for up counting and down counting. So the issue.
regards

 

[addn]

counting direction

hi,anoop12

had you try my way in your last post"dual clock counter"?

 

[anoop12]

Re: counting direction

hello addn,
yes , it works fine. But the problem is how to utilize the flag signal from the circuit that you gave in counter program.

 

[aajizattari]

counting direction

I am a beginner

I tried .... but the construct is not Synthesizeable


Now I ask you people


Of the two clocks which one will be our reference ???

i.e. When will the count be updated in count register


I would like to know the particular use of such a counter

In my opinion it must have two Enable inputs a least one for each clock

 

[echo47]

counting direction

The 74193 is an ancient TTL counter that contains a gated clock and asynchronous logic (a set-reset flop that remembers which clock was pulsed). Consider using modern synchronous FPGA/CPLD design instead. Or are you required to emulate the 74193 for a school assignment?